Containers for containing a liquid are used in numerous devices. In many applications, it is intended to heat a quantity of liquid. This is realized by providing a container having an appropriate volume, and incorporating the container in a device, wherein furthermore heating means are provided and incorporated in the device as well. When the heating means are activated, the content of the container is heated to a desired temperature, and the hot liquid is further applied as desired.
In many cases, it is advantageous and practical if the container has a closed housing. However, when liquid is heated inside a closed space, pressure builds up inside that space, especially when the liquid is made to boil. Therefore, in such a case, it is advantageous to have a vent pipe which is arranged at a top position of the container, and which is adapted to let out gas such as air and steam, and, if necessary, liquid that is excess liquid due to expansion of the liquid. Without a vent pipe, there is a risk that pressure inside the container gets too high, as a result of which the container could be damaged.
Naturally, for a vent pipe to work properly and actually realize a pressure reducing effect, it is important that the vent pipe is open and that measures are taken for avoiding blockage of the vent pipe. For example, when water is boiled inside a container, there is a risk that particles such as pieces of bio film, scale particles, parts of packaging material and/or polystyrene parts plug the vent pipe and significantly reduce the pressure reducing function of the vent pipe. Also, when the application of the container is such that frequent cleaning is required, the particles may comprise pieces of cloth, pieces of sponge, etc. The particles are often capable of floating on the liquid, as a result of which the particles can actually reach the vent pipe. Regardless of the specific type of particles, blockage of the vent pipe by particles needs to be prevented, so that the pressure reducing function of the vent pipe is guaranteed, and dangerous situations cannot occur.
A well-known solution involves providing a mesh or screen at a suitable position in the container. However, over time, such a mesh or screen gets clogged with all kinds of particles. The more the mesh or screen gets contaminated, the less the pressure reducing function of the vent pipe is. Eventually, if the contamination is not noticed in time, the vent pipe may get clogged after all, so that there is still a risk of damage of the container.
JP2004299766A discloses a container suitable for containing water, comprising fluid outlet means having a hole for allowing fluid to escape, wherein a surface defining the hole is provided with at least one recessed portion.